Electrical machine comprising brush holder that can be simply positioned and mounting method for electric machine

ABSTRACT

An electrical machine including a brush holder disposed in a housing with the housing and/or housing cap having an elastic region which enables positioning of the brush holder relative to a commutator from outside the housing. An installation method for installing a brush holder of an electrical machine is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 35 USC 371 application of PCT/DE2004/001127 filedon Jun. 2, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electrical machine with a brushholder, which makes simple and secure positioning of the brush holderpossible. The present invention also relates to a method for installinga brush holder of an electrical machine.

2. Description of the Prior Art

Electrical machines are well known in the prior art. In particular,electrical machines that include a brush holder which holds brushes thatare in contact with a commutator disposed on the rotor shaft are known.If high efficiency of the electrical machine is to be achieved, thebrushes must be aligned in a correct position relative to thecommutator. Because of production variations, or tolerances, in theindividual parts of the electrical machine, it is necessary for thebrush holder in particular to be aligned relative to the commutatorafter installation, in order for the brushes to be positioned correctly.The alignment of the brush holder is done via openings which areprovided in the housing or in the housing cap of the electrical machineand which are closed again by means of a small additional cap after thebrush holder has been aligned. Often, however, the fields in which theelectrical machines are used require them to be watertight. For thisreason, the openings present for the alignment of the brush holder mustbe closed tightly after the alignment. This presents an additional riskof a leak. Watertight electrical machines of this kind are used forinstance as drives for windshield wipers in vehicles.

SUMMARY AND ADVANTAGES OF THE INVENTION

The electrical machine of the invention has the advantage over the priorart that no additional opening has to be provided in the housing or inthe housing cap of the electrical machine for aligning the brush holder.This is achieved according to the invention by providing that in thehousing and/or in the housing cap of the electrical machine, an elasticregion is provided by way of which positioning of the brush holder ispossible from the outside of the electrical machine. As a result,according to the invention, a seal required for an additional cap forclosing the alignment opening in the prior art can be dispensed with.

The elastic region for aligning the brush holder is preferably disposedin the housing cap of the electrical machine.

Especially preferably, the elastic region is formed by an elastomerelement secured in the housing or the housing cap. The elastomer elementcan be secured, for instance by means of welding or some other method,in the housing or in the housing cap before installation. In theuninstalled state of the electrical machine, the securing of theelastomer element can be done without major effort. As a result,adequate sealing is attained even though the housing or housing cap hasthe elastomer element as an additional element.

The elastomer element is furthermore preferably an elastomer diaphragm.

In another preferred feature of the present invention, the elasticregion is embodied integrally with the housing and/or the housing cap.This alternative has the great advantage that no additional element isprovided in the housing or the housing cap, so that one sealing pointcan be dispensed with. This also has advantages in terms of productionand assembly. Especially preferably, the integrally formed elasticregion is formed by a wavelike structure in the housing or in thehousing cap. An annular wavelike structure is especially preferred.Alignment of the brush holder installed in the housing can then be doneespecially simply by way of the region enclosed by the wavelikestructure.

Especially preferably, the electrical machine is designed to bewatertight. This can be accomplished for instance by providing a sealbetween the housing and the housing cap.

The electrical machine of the invention is preferably used in a vehicle,in particular as a drive for electrically actuated accessories, such aswindshield wipers or the like.

In the installation method for installing a brush holder in anelectrical machine, the brush holder is first introduced into a housingcomponent, and the further components of the electrical machine areinstalled in the housing. Next, the housing component is closed by meansof a housing cap, and then the brush holder is positioned in its finalplace via an elastic region embodied in the housing or in the housingcap. Thus the elastic region of the invention on the housing or thehousing cap makes final positioning of the brush holder possible fromoutside the electrical machine. As a result, closure of the openingsotherwise provided in the housing for positioning the brush holder canbe dispensed with. Moreover, for instance after a certain number ofhours of operation, simple positioning of the brush holder can be donefrom outside as needed, in the event that the brush holder has changedposition as a consequence of operation.

Especially preferably, the final positioning of the brush holder is doneby means of a die element positioned from outside against the housing oragainst the housing cap.

BRIEF DESCRIPTION OF THE DRAWINGS

A plurality of exemplary embodiments of the present invention aredescribed below in detail, in conjunction with the drawings, in which:

FIG. 1 is a schematic sectional view of an electrical machine in a firstexemplary embodiment of the present invention;

FIG. 2, a schematic perspective sectional view of the housing cap usedin FIG. 1; and

FIG. 3, a schematic sectional view of an electrical machine in a secondexemplary embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An electrical machine 1 in a first exemplary embodiment of the presentinvention will now be described, in conjunction with FIGS. 1 and 2.

As shown in FIG. 1, the electrical machine 1 includes a housingincluding a body 2 and a housing cap 3, and a brush holder 5. The brushholder 5 is disposed in the interior of the housing and serves to holdbrushes 6 that rest on a commutator 7. The commutator 7 is disposed on arotor shaft 8 in a known manner. An elastomer element 4 is also disposedin the housing cap 3.

As FIG. 2 shows, the elastomer element 4 is disposed in the middle ofthe housing cap 3 and is essentially cylindrical in shape. To achievesecure sealing off from the housing cap 3, a fastening slot is providedin the outer circumference of the cylinder, so that as FIG. 2 shows indetail, a double sealing is achieved between the elastomer element 4 andthe housing cap 3. For safety's sake, the elastomer element 4 can alsobe welded to the housing cap 3. A seal 9 is also embodied between thehousing cap 3 and the housing. The electrical machine 1 of the firstexemplary embodiment is used as a wiper motor in vehicles and musttherefore be watertight.

As indicated in FIG. 1, once the electrical machine has been fullyassembled, an alignment of the brush holder 5 relative to the commutator7 is performed. To that end, a die element 10 is guided from outside theelectrical machine 1 against the elastomer element 4, as shown inFIG. 1. The die element 10 exerts a predetermined force F on theelastomer element 4 to enable final positioning of the brush holder 5relative to the commutator 7. As a result, production-dictatedvariations can be compensated for without providing an opening in thehousing or the housing cap that has to be closed again after thepositioning is done. The brush holder 5 is disposed in the housing insuch a way that to a certain extent it can vary its position relative tothe commutator 7. This can be attained for instance by way of a slightpress fit between the brush holder 5 and the housing 2.

The electrical machine 1 of the invention can thus also meet therequirement, necessary for its use as a wiper motor in vehicles, interms of watertightness without having to accept sacrifices in terms ofquality that can occur because of different tolerances of the variousindividual components. Final positioning of the brush holder 5 can beperformed markedly more simply than in the prior art.

A second exemplary embodiment of the present invention will now bedescribed, in conjunction with FIG. 3. Parts that are the same orfunctionally the same are identified by the same reference numerals asin the first exemplary embodiment.

The second exemplary embodiment is substantially equivalent to the firstexemplary embodiment, and therefore only differences between them willbe described in detail below. As can be seen from FIG. 3, instead of theelastomer element, the housing cap 3 has an elastic region 11 that isformed integrally with the housing cap 3. The elastic region 11 has awavelike structure and is formed annularly. As a result as shownschematically in FIG. 3, a die element 10 can be positioned against theportion 12 surrounded by the elastic region 11 and can deform thehousing cap 3 with a predetermined force F. In the process, the interiorof the housing cap 3 comes into contact with the brush holder 5, so thatwhen the housing cap 3 has been installed, positioning of the brushholder 5 is possible relative to the housing body 2 and to thecommutator 7. This exemplary embodiment ha the particular advantage thatthe elastic region 11 is formed integrally with the housing cap 3. As aresult, there are no sealing problems whatever. Moreover, the elasticregion 11 can be produced jointly with the production of the housing cap3 in a simple way. Especially preferably, the housing cap 3 is made froma plastic material or a spring steel. Once the brush holder 5 has beenaligned in its final position, the housing cap 3, after the die forced Fis withdrawn, resumes its original shape. If during operation of theelectrical machine realignment of the brush holder 5 relative to thecommutator 7 should become necessary, this can be done in a simple wayby positioning the die element 10 against the portion 12 surrounded bythe plastic region.

The electrical machine of the invention is used preferably in vehicles,in which the electrical machine may have watertight properties. Forinstance, the electrical machine is used as a wiper motor for windshieldwipers or as a drive for other electrically actuated accessories.

The foregoing relates to preferred exemplary embodiments of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

1. An electrical machine, comprising a housing for the machine, thehousing including a housing body (2) and a housing cap (3), a brushholder (5) disposed in the housing for holding brushes (6), and anelastic region (4; 11) in the housing cap (3) which enables positioningof the brush holder (5) relative to a commutator (7) from outside thehousing, wherein the elastic region (4) is embodied as an independentlyformed elastomer element disposed in and secured in the housing cap (3),and wherein a seal is achieved between the elastomer element and thehousing cap (3), wherein the elastomer element secured in the housingcap (3) is shaped as a cylinder and which is provided with a fasteningslot in an outer circumference of the cylinder thereby achieving theseal between the elastomer element and the housing cap.
 2. An electricalmachine, comprising a housing for the machine, the housing including ahousing body (2) and a housing cap (3), a brush holder (5) disposed inthe housing for holding brushes (6), and an elastic region (4; 11) inthe housing cap (3) which enables positioning of the brush holder (5)relative to a commutator (7) from outside the housing, wherein theelastic region (4) is embodied as an independently formed elastomerelement disposed in and secured in the housing cap (3), and wherein aseal is achieved between the elastomer element and the housing cap (3),wherein a fastening slot is provided in the outer circumference of thecylinder, so that a double seal is achieved between the elastomerelement 4 and the housing cap
 3. 3. An electrical machine, comprising ahousing for the machine, the housing including a housing body (2) and ahousing cap (3), a brush holder (5) disposed in the housing for holdingbrushes (6), and an elastic region (4; 11) in the housing cap (3) whichenables positioning of the brush holder (5) relative to a commutator (7)from outside the housing, wherein the elastic region (4) is embodied asan independently formed elastomer element positioned within and securedto the housing cap (3), and wherein a seal is achieved between theelastomer element and the housing cap (3), and wherein the housing cap(3) is rigid relative to the independently formed elastomer element. 4.The electrical machine according to 3, wherein the elastomer elementsecured in the housing cap (3) is shaped as a cylinder.
 5. Theelectrical machine according to claim 3, wherein the elastomer elementis an elastomer diaphragm.
 6. The electrical machine according to claim3, wherein the electrical machine is embodied as watertight.
 7. Theelectrical machine according to claim 3, wherein the electrical machineis used in a vehicle as a drive for electrically actuated accessories.8. The electrical machine according to claim 3, wherein the electricalmachine is used in a vehicle as a drive for windshield wipers.
 9. Theelectrical machine according to claim 3, wherein the brush holder (5) isdisposed in the housing body (2) by a slight press fit.
 10. Theelectrical machine according to claim 3, wherein a seal (9) is embodiedbetween the housing cap (3) and the housing body (2).
 11. The electricalmachine according to claim 3, wherein the elastomer element (4) iswelded to the housing cap (3).
 12. The electrical machine according toclaim 3, wherein the brush holder (5) is disposed in the housing body ina manner such that the positioning of the brush holder (5) relative tothe commutator (7) is variable.
 13. The electrical machine according toclaim 3, wherein a press fit exists between the brush holder (5) and thehousing (2).
 14. The electrical machine according to claim 3, wherein adie element (10) guided from outside the housing cap (3) and pressedagainst the elastomer element (4) with a predetermined force F, enablesa final positioning of the brush holder (5) relative to the commutator(7).